DISSERTATION RESEARCH: Genetic consequences of the shift to asexuality in bryophytes: Insights from the hornwort <I>Megaceros aenigmaticus</I>

金鱼藻是生长在潮湿、潮湿的生境中的原始植物，缺乏种子和维管组织。这些简单的植物表现出复杂多样的繁殖系统，一些物种进行有性繁殖，另一些物种进行无性繁殖。植物无性进化的原因及其对遗传变异的影响是植物进化中的重要问题。这个项目将研究生长在阿巴拉契亚山脉南部的一种金鱼草的有性繁殖损失。这些无性繁殖的角藻被认为是阿巴拉契亚山脉特有的物种。但最近在哥斯达黎加发现了该物种的其他成员，在那个地方该物种进行了有性繁殖。利用基因序列数据，研究人员将确定阿巴拉契亚和哥斯达黎加犀牛种群的关系，以及自然种群中性别丧失对遗传变异的影响。这项工作将解决自然种群中植物性别进化和遗传变异的广泛问题。这项研究将提供与北美这种不寻常的金鱼草保护相关的科学数据。这位研究生将参加当地的生物多样性活动，如生物闪电战，这是一项公民科学活动，让普通公众参与到一个地区的物种普查中，他将在大烟山国家公园和其他场所发表公开演讲。这项研究将支持与中美洲研究人员的几个国际合作项目。

Hornworts are primitive plants growing in damp, humid habitats that lack seeds and vascular tissue. These simple plants exhibit a complex variety of breeding systems, with some species engaging in sexual reproduction and others propagating asexually. The reasons for the evolution of asexuality and its effects on genetic variation in plants are important issues in plant evolution. This project will examine the loss of sexual reproducing in a species of hornwort growing in the Southern Appalachian Mountains. These asexual hornworts were thought to be an endemic species restricted to the Appalachians. But recently other members of the species were found in Costa Rica, and in that locale the species reproduces sexually. Using gene sequence data the researchers will determine the relationships of the Appalachian and Costa Rican hornwort populations and the effect of the loss of sex on genetic variation in natural populations. The work will address broad issues in the evolution of plant sexuality and genetic variation in natural populations.The research will provide scientific data relevant to the conservation of this unusual hornwort in North America. The graduate student will participate in local biodiversity activities such as BioBlitz, a citizen science activity involving the general public in making a census of species in an area, and he will present public lectures at the Great Smoky Mountain National Park and other venues. The research will support several international collaborative projects with researchers in Central America.